AJP - Heart and Circulatory Physiology, Vol 258, Issue 1 92-100, Copyright © 1990 by American Physiological Society

ARTICLES

Pulsatile pressure can prevent rapid baroreflex resetting

D. Mendelowitz and A. M. Scher
Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle 98195.

In a previous study [Am. J. Physiol. 255 (Heart Circ. Physiol. 24): H673-H678, 1988] we demonstrated that baroreflex responses decay (reset) to increased static sinus pressures, but with increased pulsatile pressure, responses are maintained. To determine more conclusively whether pulsatile pressure prevents rapid baroreflex resetting in this study we examined resetting as shifts of the baroreflex (sinus pressure-arterial pressure) curve. In seven anesthesized rabbits the left sinus was vascularly isolated and conditioned for 5 min to static or pulsatile pressures of 60, 100, or 140 mmHg mean pressure, 0 or 35-40 mmHg pulse pressure. The baroreflex curve was then determined by stepwise changing sinus pressure from 40 to 160 mmHg in 20-mmHg increments. Threshold, midpoint, and saturation sinus pressures shifted 25-39% with static conditioning pressures but did not shift significantly with pulsatile pressures. Also, the baroreflex responses to step increases in static sinus pressure decayed, as resetting occurred, but did not decay with pulsatile sinus pressure increases. Thus the baroreflex rapidly resets with static pressures, but there is minimal, if any, resetting with pulsatile pressures.

This article has been cited by other articles:

				R. Zhang, K. Behbehani, C. G. Crandall, J. H. Zuckerman, and B. D. Levine Dynamic regulation of heart rate during acute hypotension: new insight into baroreflex function Am J Physiol Heart Circ Physiol, January 1, 2001; 280(1): H407 - H419. [Abstract] [Full Text] [PDF]

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